Question

gente, me ajudem, é urgente!

1- 2x+y=10
-x+3y=2

3- 3x+y=12
x-5y=4

4- x=8y
2y+x=5

5- x-2y=-2
x+y=-6

Answer 1

1)

{ 2x+y=10*(-3)
{-x+3y=2
:
:
{y=10-2x
{-x +3y=2
:
:
-x+3 (10 -2x)=2
-x+30-6x=2
-x-6x=2-30
-7x=-28
x=28/7
x=4


2x+y=10
2*(4)+y=10
8+y=10
y=10-8
y=2



s ( 4 , 2 )



2)

{3x+y=12
{x-5y=4
:
:
{y=12-3x
{x-5y=4
:
:
x-5 (12-3x)=4
x-60+15x=4
x+15x=4+60
16x=64
x=64/16
x=4

y=12 - 3*4
y=12 -12
y=0


s ( 4 , 0 )



3)


{x=8y
{2y+x=5


2y+8y=5
10y=5
y=5/10
y=1/2

x=8*1/2
x=4

s ( 4 , 1/2)




4)

{x-2y=-2
{x+y=-6*(2)
:
:
{x-2y=-2
{2x+2y=-12
-----------------(+)
3x= -14
x= -14/3


x-2y=-2
-14/3-2y= -2
-2y= -2+14/3
2y= 2 -14/3
2y= 6 -14/3
2y= -8/3
y= -8/3/2
y= -8/3 * 1/2
y= -8/2
y= -4



s ( -14/3 , -4 )